如何在Django中设置文件的动态路径

Question

I working on a project that User (customer) can login and can view information about his invoices, download them ( in Pdf format ) etc.

When User setted up in admin panel, his pdf files is uploaded ( User can have many Pdf files )

When Pdfs is uploaded, a function create folders based on his id, and put them in, so i have to create a dynamicaly function that downloads the correct pdf file when User click on it.

This is a for in html that prints all "charges" to user:

{% for printforme in print_user_charges %}
        <tr>
          <td>{{ printforme.invoice_number }}</td>
          <td>{{ printforme.price }} €</td>
          <td>{{  printforme.reason }}</td>
          <td>{{ printforme.customer }} {{ printforme.customer.surname }}</td>
          <td>{{ printforme.charge_date }}</td>
          <td>  <a href="{% url 'download_pdf' printforme.id %}"> Download </a></td>

{% endif %}

Even i try to create a function that sets the path dynamicaly and converting it to a string django tells me that expects a string and not a function.

def DownloadPdf(request, charge_id):                                                                                                                            

with open(os.path.join(settings.MEDIA_ROOT,models.Charge.upload_pdf.url, 'rb') as fh:     
    response = HttpResponse(fh.read(), content_type="application/pdf")   
    response['Content-Disposition'] = 'filename=invoice.pdf'             
    return response                                                      

I want to insert the url of the selected pdf base to the id. But i donw know how to pull out the url and link it with the other media path and use corrrectly the id.

edit

if i change to this:

    url(r'^download/(?P<charge_id>\d+)/$', views.DownloadPdf, name='download_pdf'),

and this:

with open(os.path.join(settings.MEDIA_ROOT, charge_id), 'rb')

it gives me that error:

Reverse for 'download_pdf' with arguments '('/media/user_4/invoice-alex-1.pdf',)' and keyword arguments '{}' not found. 1 pattern(s) tried: ['download/(?P\\d+)/$']

Answer 1

You need not write a view to handle the download part. Browsers today are smart enough to handle the download part. In your template, just do the following (assuming that at template level your are aware who is user and what sort of file is to be downloaded for him. Just pass all this info in the context of the view where the user will have the authority to download stuff.):

<a href="{{MEDIA_URL}}<your_file_with_id.pdf>">Download File</a>

And that's it. The browser will automatically download the file. You need not do anything else.

Answer 2

After all i find a working solution

My main problem it was that i was try to get an instance and i do not pass it into any variable before i try to load the file. I change the open method to, i found the last one more clear.

def DownloadPdf(request, charges_id):

try:
    invoice = Charge.objects.get(pk=charges_id)
except Charge.DoesNotExist:
    raise Http404

response = HttpResponse(File(invoice.upload_pdf), content_type="application/pdf")
response['Content-Disposition'] = 'attachment; filename="mypdf.pdf"'
return response